The development of the EDVAC computer system of 1948 is often cited as the beginning of the computer era. Since that time, computer systems have evolved into extremely sophisticated devices capable of storing and retrieving vast quantities of data. This data is often stored on a computer in units called files, and computers often have a large number of files. Users commonly save multiple versions of the same file, each version having slightly or drastically different data from the other. For example, different versions of a file called “Product Documentation” might contain documentation describing different releases of a product. With so many files and so many versions of files, users can quickly become confused as to which version of which file contains which data. To assist users in differentiating versions of files, tools are available that compare two versions of a file, and generate a result that illustrates how the versions are different.
These compare tools work well when the changes from one version to the next are simple word revisions, spelling error corrections, or changes from one word to a more appropriate word. Unfortunately, some versions of files are so drastically different from a previous version that the compare tools can generate a result that is very difficult for the reader to understand.
For example, some compare tools show each word or phrase that has been deleted, usually in strike-through font, immediately followed by the word or phrase that replaces it, often in a special color. This works well for small changes such as spelling corrections, but reviewers may have difficulty reading this format when changes are sprinkled throughout a paragraph, especially when the meaning of the paragraph has changed.
In an attempt to address this problem, some compare tools work on a line-by-line basis, showing, often side-by-side, the old lines next to the new lines, lining up and highlighting the regions that have changed. This works well for files that have major changes, but is problematic in that the reviewer may easily miss which words, characters, or punctuation have actually changed in each line.
Without a compare tool that works well for a variety of revision types, users will continue to be frustrated in their attempt to distinguish between multiple versions. Although the aforementioned problems have been described in the context of multiple versions of text files, they can also apply to other types of data.